The present invention relates to a device for supplying electric current to an electric drive, to a drive train for a vehicle and to a method for supplying electric current to an electric drive.
In order to increase the range of electrically driven vehicles, it is known from the prior art to provide a plurality of, in particular different, energy sources. For mutual charge balancing of the energy sources, said energy sources are connectable to one another. Furthermore, the energy sources are also connected to the electric drive in order that current can be supplied to said electric drive. For this purpose, it is known from the prior art to connect DC-to-DC converters in series with the individual electrical energy sources in order that the respective output voltage of the individual energy sources can be adjusted to a presettable voltage level. For example, the Japanese laid-open specification JP 2011-36101 A1 discloses a design comprising three DC-to-DC converters. A first energy source, in this case a fuel cell, is in this case used simultaneously for supplying a high voltage to an electric drive and for supplying a relatively low voltage to further consumers in the electrical distribution system of the vehicle. For this purpose, two DC-to-DC converters are connected to this energy course, to which DC-to-DC converters in each case the desired output voltage is provided on the output side. In the example illustrated, a second energy source is connected directly to the electric drive. The electric drive is connectable directly to the consumers of the vehicle electrical distribution system via a third DC-to-DC converter. Therefore, the possibility is provided of supplying electrical energy to the vehicle electrical distribution system by means of the second energy source as well, or recuperatively by means of the electric drive. Variable adjustment of the output voltage of the second energy source in accordance with the requirement of the electric drive is not possible with this circuit since the second energy source is connected directly to the electric drive.